Veritas-bu

[Veritas-bu] Expert advice

2005-10-20 16:19:33
Subject: [Veritas-bu] Expert advice
From: ewilts AT ewilts DOT org (Ed Wilts)
Date: Thu, 20 Oct 2005 15:19:33 -0500
On Thu, Oct 20, 2005 at 12:09:35PM -0600, Mark.Donaldson AT cexp DOT com wrote:
> To optimize for restorals, I'd:
>  
> 1. Turn off multiplexing - mpx doesn't hurt you for single-file restore but
> it can cost big on whole server/filesystem restores.

Turning multiplexing off can really hurt your backups - if you can't
drive the tape drive at full speed, you'll shoeshine.

> 2. Use fragments on your storage units.  I use 4096M per fragment for my
> tapes.  This allows faster search-to-file ability at the cost of a larger
> catalog.

The larger the fragment size, the faster your *FULL* restores will be.
However, your individual file restores will be slower - on average,
they'll need to read 2GB of data off the tape instead of 1GB.

To optimize for restores, though, I'd do all my backups to disk or at
least disk staging.  

Use FlashBackup if you can since your restores will be significantly
faster - we see at least double the throughput with FlashBackups than
walking the file system if you have lots of small files.

-- 
Ed Wilts, Mounds View, MN, USA
mailto:ewilts AT ewilts DOT org

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